The beginning of a little experiment....
The 17-40mm f/4 "L" is supplied with what looks like one of the most useless lens hoods around. Like any lens hood desighned to work on a Zoom lens, it's only really effective when the lens is Zoomed to its widest setting. However in the particular case of the 17-40mm, the extremity to which this occurs is most prominenet.
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Add to that fact a 1.6 crop factor of a Canon DSLR,. and the resulting combination is a completely useless lens hood. In the case of the 1.6X focal plane of the DSLR, even at 17mm the lens hood is much too wide and short to be efective.. zoomed in to 40mm,.. this lens hood is doing absolutely nothing.
My first attempt at a solution involved the lens hood from my telephoto Sigma 70-200mm which shares the 17-40mm's 77mm filter size.
Amazingly,. this lens hood actually "sort of" fits!
The results though were not perfect. The 70-200mm lens hood is either too long,. or not wide enough (it has a much narrower "bell" than the 17-40mm's hood)
BUT!
Believe it or not this telephoto lens' very long narrow lens hood worked with the 17-40mm perfectly from 40mm down to about 25mm.
Vignetting did not start untill 24mm!!
This went a long way to illustrate how woefully inadaquate the stock lens hood was for anything other than 17mm on a full 35mm focal plane camera!
So I took a gamble on all of Canons 77mm threaded lenses having the same mount for a lens hood,. and I ordered the much more substantial EW-83B.
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This Vs. the rather idiotic looking stock Hood the EW-83E
(DUPLICATE IMAGE)
It arrived today (I was able to get it for $11.00 from MPSuperstoors!!!! B&H Sells it for $47.00!)
This lens hood is just as long as the Sigma 70-200mm's lens hood,. but it also has a wider "bell"
Well the gamble paid off,. the hood snaps onnto the 17-40mm jsut as well as the stock hood does.
RESULTS?
Again it functions from the lenses narrowest setting of 40mm, but this time all the way down to 21mm before any sighns of vignetting.
So now the next step,.. do I keep the seperate hood for use on the lens with shots 21mm or wider? Or do I cut the hood down untill it functions all the way down to 17mm on the DSLR's 1.6 crop factor and thus cripple it's usefullnes for any of the narrower end of the zoom?
Hmmmmmmmmmm............
